This invention relates to an intravascular catheter useful for extracorporeal blood circulation through an artificial kidney, an artificial lung, or the like.
In a conventional blood dialyzing operation using an artificial kidney, a couple of needles are kept inserted respectively to each of the vein and artery of a patient for the suction and recovery of blood through the artificial kidney. In this case, the patient is obliged to suffer from a great deal of pain because two needles are stuck to his blood vessels. In addition, the life of the shunt serving to connect directly the artery and the vein tends to be shortened.
To overcome the above-noted drawbacks, a so-called "single needle system" has been proposed in which withdrawing from and returning to the body of the blood are effected by using a single needle. In this case, the opening-closing of a valve is performed electrically so as to enable the single needle to withdraw and return the blood alternately. The alternate operation naturally leads to a longer dialyzing time than for the case of using two needles, because shortening of the dialyzing time, will cause sharp and enlarged fluctuations in the internal pressure of the dialyzing circuit, giving bad influences to the patient. It should also be noted that the single needle system necessitates a particular machine for operating the circulation.